mpc5777c CSE load key

[InhyeokHwang]

Hi NXP teams

I'm currently studying on cse_keyconfig_mpc5777c example code from s32 ds pa 2.1 and I found something strange in the code which I don't get it.

According to the reference manual, all M1, M2, M3, M4, M5 should be computed and used for the load key command.

But in the example code, I only can see computeM1M2M3 function inside load key command and have no idea why computeM4M5 is not being used.

When I try to find the usage of computeM4M5 in the project using ctrl+h, this function is used nowhere. 

Thanks in advance

[lukaszadrapa · Accepted solution]

Hi @InhyeokHwang 

the thing is that M1-M3 are input parameters needed to load a key, M4-M5 values are output values.

M4-M5 values should be used to verify if a key was loaded correctly. If returned M4-M5 values match with M4-M5 values calculated offline, it's a proof that the key was loaded correctly. In the real application, it's highly recommended to do this checking, of course. Project cse_keyconfig_mpc5777c is example only, it's not implemented for some reasons.

Regards,

Lukas

[InhyeokHwang]

thanks for the reply. I appreciate it